package com.ygl.gateway.util;

import com.google.common.collect.Maps;
import io.jsonwebtoken.*;
import io.jsonwebtoken.security.Keys;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.codec.binary.Base64;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import javax.crypto.SecretKey;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

/**
 * @Author yanggld
 * @Date 2019/12/2-16:29
 * @Description
 */
@Slf4j
@Component
public class JwtUtil {
	/**
	 * 秘钥
	 * - 默认aaabbbcccdddeeefffggghhhiiijjjkkklllmmmnnnooopppqqqrrrsssttt
	 */
	@Value("${secret:aaabbbcccdddeeefffggghhhiiijjjkkklllmmmnnnooopppqqqrrrsssttt}")
	private String secret;
	/**
	 * 有效期，单位秒
	 * - 默认2周
	 */
	@Value("${expire-time-in-second:1209600}")
	private Long expirationTimeInSecond;

	/**
	 * 从token中获取claim
	 *
	 * @param token token
	 * @return claim
	 */
	public Claims getClaimsFromToken(String token) {
		try {
			return Jwts.parser()
					.setSigningKey(this.secret.getBytes())
					.parseClaimsJws(token)
					.getBody();
		} catch (ExpiredJwtException | UnsupportedJwtException | MalformedJwtException | IllegalArgumentException e) {
			log.error("token解析错误", e);
			throw new IllegalArgumentException("Token invalided.");
		}
	}

	/**
	 * 获取token的过期时间
	 *
	 * @param token token
	 * @return 过期时间
	 */
	public Date getExpirationDateFromToken(String token) {
		return getClaimsFromToken(token)
				.getExpiration();
	}

	/**
	 * 判断token是否过期
	 *
	 * @param token token
	 * @return 已过期返回true，未过期返回false
	 */
	private Boolean isTokenExpired(String token) {
		Date expiration = null;
		try {
			expiration = getExpirationDateFromToken(token);
		} catch (Exception ex) {
			return true;
		}
		return expiration.before(new Date());
	}

	/**
	 * 计算token的过期时间
	 *
	 * @return 过期时间
	 */
	private Date getExpirationTime() {
		return new Date(System.currentTimeMillis() + this.expirationTimeInSecond * 1000);
	}

	/**
	 * 为指定用户生成token
	 *
	 * @param claims 用户信息
	 * @return token
	 */
	public String generateToken(Map<String, Object> claims) {
		Date createdTime = new Date();
		Date expirationTime = this.getExpirationTime();
		byte[] keyBytes = secret.getBytes();
		SecretKey key = Keys.hmacShaKeyFor(keyBytes);
		return Jwts.builder()
				.setClaims(claims)
				.setIssuedAt(createdTime)
				.setExpiration(expirationTime)
				// 你也可以改用你喜欢的算法
				// 支持的算法详见：https://github.com/jwtk/jjwt#features
				.signWith(key, SignatureAlgorithm.HS256)
				.compact();
	}

	/**
	 * 判断token是否非法
	 *
	 * @param token token
	 * @return 未过期返回true，否则返回false
	 */
	public Boolean validateToken(String token) {
		if (StringUtils.isEmpty(token)) {
			return false;
		}
		return !isTokenExpired(token);
	}

	public static void main(String[] args) {
		// 1. 初始化
		JwtUtil jwtOperator = new JwtUtil();
		jwtOperator.expirationTimeInSecond = 1209600L;
		jwtOperator.secret = "aaabbbcccdddeeefffggghhhiiijjjkkklllmmmnnnooopppqqqrrrsssttt";

		// 2.设置用户信息
		HashMap<String, Object> objectObjectHashMap = Maps.newHashMap();
		objectObjectHashMap.put("id", "1");

		// 测试1: 生成token
		String token = jwtOperator.generateToken(objectObjectHashMap);
		// 会生成类似该字符串的内容: eyJhbGciOiJIUzI1NiJ9.eyJpZCI6IjEiLCJpYXQiOjE1NjU1ODk4MTcsImV4cCI6MTU2Njc5OTQxN30.27_QgdtTg4SUgxidW6ALHFsZPgMtjCQ4ZYTRmZroKCQ
		System.out.println(token);

		// 将我改成上面生成的token!!!
		String someToken = "eyJhbGciOiJIUzI1NiJ9.eyJpZCI6IjEiLCJpYXQiOjE1NzUyNzYwMjEsImV4cCI6MTU3NjQ4NTYyMX0.zLBl4MmqIbZ3Fs2VGRkCmRiYR5yzw2Z3-mCgBD9fDko";
		someToken = token;
		// 测试2: 如果能token合法且未过期，返回true
		Boolean validateToken = jwtOperator.validateToken(someToken);
		System.out.println(validateToken);

		// 测试3: 获取用户信息
		Claims claims = jwtOperator.getClaimsFromToken(someToken);
		String subject = claims.getSubject();
		System.out.println("subject:"+subject);
		Object id = claims.get("id");
		System.out.println("id:"+id);
		System.out.println(claims);

		// 将我改成你生成的token的第一段（以.为边界）
		String encodedHeader = "eyJhbGciOiJIUzI1NiJ9";
		encodedHeader = token.split(".")[0];
		// 测试4: 解密Header
		byte[] header = Base64.decodeBase64(encodedHeader.getBytes());
		System.out.println(new String(header));

		// 将我改成你生成的token的第二段（以.为边界）
		String encodedPayload = "eyJzdWIiOiJuYWNvcyIsImF1dGgiOiIiLCJleHAiOjE1NzU1MjY2MTN9";
		encodedPayload = token.split(".")[1];
		// 测试5: 解密Payload
		byte[] payload = Base64.decodeBase64(encodedPayload.getBytes());
		System.out.println(new String(payload));

		// 测试6: 这是一个被篡改的token，因此会报异常，说明JWT是安全的
		jwtOperator.validateToken("eyJhbGciOiJIUzI1NiJ9.eyJpZCI6IjEiLCJpYXQiOjE1NjU1ODk3MzIsImV4cCI6MTU2Njc5OTMzMn0.nDv25ex7XuTlmXgNzGX46LqMZItVFyNHQpmL9UQf-aUx");
	}
}
